Insight into carbonyl source based on improved source apportionment method: Alkene regulate secondary formation
Yulong Yan1, Yueyuan Niu2, Xiaolin Duan3
1Engineering Research Center of Clean and Low-carbon Technology for Intelligent Transportation, Ministry of Education, School of Environment, Beijing Jiaotong University, Beijing 100044, China; School of Environment, Beijing Jiaotong University, Beijing 100044, China.
Abstract:
Carbonyls can be emitted by human activities or produced by photochemical oxidation. However, there is a lack of accurate methods for separately analyzing the primary and secondary sources of carbonyls, which is important for industrial cities with large carbonyls emission. Combined the method of multiple linear regression, positive matrix factorisation (PMF) and observation-based model (OBM), this study improved the source apportionment method of carbonyl and conducted research in a typical industrial city in North China during different seasons. In the method, the source of primary emissions and secondary formation of carbonyls were analysed separately. The concentrations of carbonyls in summer were 47 % higher than those in winter, and acetaldehyde was present in the highest concentrations. Acetaldehyde was mainly formed by secondary formation in summer (51 %) but by primary emissions (40 %) in winter, owing to high temperatures and strong photochemical reactions during summer. The PMF results demonstrated that gasoline vehicle emissions were the major contributors (16 %) in summer. The contribution of diesel vehicle emissions was higher (7 %) in winter than in summer, which related to higher coal transport requirements in winter for industrial city. Chemical budget result indicated that RO· (from alkene) + O2 dominated the secondary formation of carbonyls, and ethylene, butene, and pentene were the main precursors. The sensitivity results for carbonyl formation highlight the importance of alkenes in secondary formation, which may be emitted from industrial processes (such as coking, steel, and cement). Therefore, different carbonyl control strategies were inferred from primary emissions and secondary formation, and comprehensive consideration was required for controlling carbonyls in the atmosphere. This study improved the source apportionment method of carbonyls, providing technical support for accurate source apportionment of carbonyl. This study provided novel insights into the control strategies for carbonyls in industrial cities.
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